Flash tube igniting device for gaseous fuel burners



June 20, 1950 c. K. STROBEL FLASH TUBE IGNITING DEVICE FOR GASEOUS FUEL BURNERS Filed Nov. 29, 1944 Top BURNER PILOT OVEN BURNER,

LIGHTER FUEL SUPPLY Patented June 20, 1950 FLASH TUBE IGNITINGFDEVICEFOR GASEOUSS FUEL BURNERS Charles K. Strob'el; Pittsburglhfai, assignor to. Robertshawf-Fultonx Controls? Company, a 0011* aeration of Delaware Application November 29, 1944; SerialNo: 565,609

1. This invention relates to lighting devices for gaseous fuel burners-and, moreparticularly, to flash tube ignition for domestic oven burners.

Devices of thisnature depend uponan openended tube of considerablelength extending between the top burnerpilot flame and the oven main'burner to the end that a fuel-air mixture entering the tube' at the oven burner end will cause the tubeto becomecompletely'filled with the combustible fluid. Thus, upon reaching the pilot burner the mixture propagates a flame which flashes back through the tube and ignites the oven burner.- In the present invention the fue l; supply for the entering fuel-air mixture is conveyed through a lighter port adjacent the oven burner and entrains its air supply after leaving the port and before entering the flashtube. Consequently, the lighter port flame which is produced after the flash-back occurs is of the yellow type for-reasons apparent hereinafter.

One object of the invention is toassist flame travel and air entrainment in a flash tube to ensure consistent ignition of the main burner.

Another object of the invention is to reduce-the heat loss from the oven chamber due to the stack action of the flash tube.

Another object of the invention is to ensure rapid and consistent ignition of theovenburner.

under either hot or cold oven condition;

Another object of the invention is to secure "of flows, pressures-and gas-air mixtures.

Another object of the invention is to eliminate critical features in the size, shape and relation ship of parts to render the device universally applicable to existing gas ranges.

Another object of the invention is to avoidinterference with saisfactoryignition due to clogging of essential orifices under service conditions.

Another object of the invention is to construct the device with relatively few parts which are simple to produce and assemble and occupy a minimum of space when installed in the range;

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a partial schematic view of a gas range showing the lighting device positioned in the oven chamber;

Fig. 2 is a partial cross section through the end' of the lighting device adjacent the oven burner; Fig. 3 is an. end elevation of. the portion of the device shown in Fig. 2; and

3 Claims; (01. 158-115):

Fig: 4 is a cross section: taken on the line:

IV -IV of Fig. 2.

Referring now more particularly to Fig; 1, the. essential parts of the gas range comprise an oven mainburner l fl positionedon'one side of an oven' wall 52 and having the usual ports ll through which" gaseous fuel-is emitted to' prod'uce a main burner flame when ignited. A top burn'erpilot Wis positioned on the other side oh the oveniwall l2 and at aconsiderably higher elevationthan the oven burner Ill; The top burner pilot I4'issupplied withfuel from any suitable source of gaseous fuel supply and produces a. name which.

may be of theconstant. burning type.

The lighting-device comprises generally aflash.

tube Hi having a laterally extending'portion. l8

at one endpositioned: adjacent the flame: of: the

top burner pilot Mt. As appears in the drawing, the lateral portion a perpendicular relationship with the vertical portion of the tube It and is gradually curved at its junction therewith. The opposite end of thetube- I6 extends laterally in the opposite di.-.-

rection from the portion I8 in the form of a curved portion and terminates at apoint spacedfromthe main burner L The tube I6 is clampedt'o-the oven wall I 2; asby the brackets 22; onthe-side opposite the oven-burner In and the curved portion 20 extends through an aperture 24 formedin the oven wall lz -for'thispur pose:

The terminal end" of the curved portion 20 is secured by an adapter 26- in sealing engagement with one member 28" of a generally cylindrical; tubular'head element, designated by the referencenumeral so. Telescopically mounted on-the member-'28'is the other member 32 of the tubular head 30. A set screw 34' projects through the member 32 into engagement with the member 28 and serves to secure these members in adjusted'relation-with a portion of member 28- projecting into theend'of-member'32'. The opposite endof the member 32 is'closed by anendportion 36 and has an inlet'connection 38 for gaseous fuel projecting laterally therefromand communicating with a suitable source of gaseous fuel supply. Preferably, thetubular-head extends at an angle of approximately degrees from the-ver-- tical portion of tube i6 intothe'oven chamber with the closed end 36' positioned adjacent the mainiburner i D; It will be apparent that the set screw 34 may be loosened-to permit adjustment of the telescoped'members- 28- and 32- to provide adesired positioning of the tubular head w with respectto-the 'oven burner l0; However, it willf I 8 may depend slightly'frombe understood that where such adjustment is not required the tubular head can be formed from a single piece of material without departure from the essential characteristics of this invention.

The member 32 is provided with a plurality of elongated openings in the side wall thereof adjacent the closed end- 36. In order to faciliv,

tate forming these openings 40, the member 32 has its outer wall formed with a triangular shaped contour, as shown in Fig. 3, and the openings 40 are formed in the triangular sides leaving three ribs 42 therebetween which connect the closed end 36 with the generally cylindrical portion of the member 32. At least one of the openings 40 extends into proximate relation with the burner ID for a purpose apparent hereinafter.

A lighter burner 44 is secured in the closed end 36 by means of a threaded projection 46 thereon and projects axially of the head 30 substantially equidistant of. the ribs 42. A port 48 extends axially through the lighter burner 44 and communicates with a passage 50 in the closed end 36 which conveys fuel from the connection 38. Preferably, a second port 52 extends substantially perpendicular to the port 48 and in communication therewith and is located on that side of the lighter burner 44 nearest to the main burner l0.

The end of the member 28 which projects into the member 32 is provided witha countersunk or annular cone-shaped portion 54 which is preferably in axial alignment with the port 48 in the lighter burne 44. The cone-shaped portion 54 has its larger end facing the lighter burner 44 and this end is substantially the same size as the boreof the member 32 leaving no appreciable annular projection at the junction therewith. The smaller end 56 of the cone-shaped portion 54 may be truncated by a junction with a larger bore 58 in the member 28. The smaller end 56 of the cone-shaped portion is of substantially the same size as the'bore of the flash tube It. Thus, the bore 58 between the cone-shaped portion 54 and the tube end 20 forms. an expansion chamber within the tubular head 30.

The expansion chamber 58 may be provided with communication with the atmosphere for use when desired. In this instance, an aperture 60 is formed through the wall of the member 28 adend 55 of the cone-shaped jacent the smaller member 54 and a set screw 52 may threadedly engage the walls of the aperture 69 forming a removable closure therefor. It will be understood thata plurality of such apertures could be provided. A collar 64 is slidably mounted on the member 32 and is adjustable by means of a clamping screw 66 therein 50 that the collar 64 may be moved partially across the adjacent triangular shaped portion to change the effective area of the openings 40.

When the flash tube l6 of this invention is installed in the range as shown schematically in Fig. 1 the open end of the portion I8 is positioned adjacent the flame of the top burner pilot Hi. The tubular head 30 is positioned so that one of the lateral openings 40 is in proximate relation with the main burner l0 which has at least one port ll directed toward the lighter burner 44. When fuel under pressure is supplied through the connection 38 to the lighter burner 44 the flow through the port 43 will entrain air" through the lateral openings 40 and the flash tube IE will become filled with a combustible fuel-air mixture. This mixture is ignited by the flame of the top burner. pilot l4 and a flash-back 4 occurs through the tube l6 and head 30 which immediately causes ignition of the lighter burner 44. If the oven burner then is receiving gaseous fuel from the same Or another source of supply as the connection 38 then a portion of the fuel from the ports 1 i will flow into lighting proximity with the burner 44. The main burner, in turn, will be ignited by the flame a'ltzthe lighter burner. The auxiliary port 52 of the lighter burner which projects towards the oven burner it facilitates the ignition thereof after the flash-back occurs. By using a flash tube constructed as described, it has been found that the tube may be of smaller bore than those previously in use without interfering with satisfactory operation. For example, the bore of the flash tube of this invention may be three-eighths inch in diameter even where tubes of two feet or more in length are used. This small size bore reduces the heat loss from the oven burner chamber by stack action, as will be apparent.

It is believed that the advantages of this invention are principally due to the provision of the expansion chamber above the cone-shaped portion, as a wide operating range in conjunction with a minimum lighter port fuel flow is obtained. Various adjustments can be made to the length of the expansion chamber, the spacing of the lighter port from the cone-shaped portion and the .air supplythrough the lateral openings to improve operation under certain lighter conditions. The latter two adjustments can easily be made by-use of the adjustable features hereinbefore described in connection with the tubular head. It is apparent that different lengths of flash tube will be required under different range designs and that installation conditions may also differ.

,As is generally known, a flash tube lighter port fuel jet, burning with a yellow flame, must entrain all of the air supply required for proper flash tube action. Any interference with free air entrainment willaifect operation of the flash tube. While it is impossible to state with certainty that the expansion chamber above the cone-shaped portion is responsible for the prevailing favorable condition in the flash tube of this invention,- it appears that it either prevents a fuel-air mixture from being forced backward through the cone-shaped portion to hinder the air entrainment or it provides a pressure release ahead of the flame which likewise prevents a decrease in air entrainment. In addition, it appears; that the truncated cone-shaped portion serves to enhance air entrainment and at the same time reduce explosive action back to the lighter port.

.The foregoing advantages are obtained withoutreiiance upon small relief openings or supplemental apertures or slots to assist air entrainment.; Consequently, there is no interference with the operation of the flash tube by clogging of such openings as has heretofore been the case and a simple i-mperforate tube may be used. However, should it be found upon installation of the flash tube in the oven that unusual conditions render communication with the atmosphere desirable, then the small relief opening provided in the expansion chamber may be resorted to by removal; of the set screw which normally closes this opening. Preferably the lighter port flame is centered relative to, the cone-shaped portion and the flame thereof is sufficiently long to project justwith'm the cylindrical end of the tubular 7s head beyond the lateral openings. Such adjustment gives satisfactory performance over a wide pressure range under both cold and hot oven conditions.

It will be apparent that various changes can be made in the arrangement and combination of parts and in the. details of construction herein disclosed within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A lighting device for a main gaseous fuel burner provided with at least one port and having a pilot burner remote therefrom and normally producing a flame, said device comprising a flash tube having one open end positioned adjacent the pilot burner and the opposite open end spaced from the main burner, a tubular head secured to said opposite tube end and terminating in a closed end adjacent the main burner, said head having a plurality of relatively spaced narrow ribs defining elongated openings in the side wall of said head adjacent said closed end, said openings being symmetrically arranged around said head and at least one of said openings being positioned to admit fuel from the one said port of the main burner into said head, an inlet connection in said closed end for fuel under pressure, a lighter burner projecting from said closed end axially of said head and terminating adjacent said openings to intercept fuel from said one port of the main burner, said lighter burner having an axial port communicating with said connection through which said fuel is adapted to flow and entrain suflicient air through said openings for filling said head and tube with a combustible fuel-air mixture to be ignited from the pilot burner and produce a flame at said lighter burner for igniting the main burner, said head having an interiorly coneshaped portion projecting from the inner wall thereof between said opposite tube end and said openings in axial alignment with said lighter burner port and being positioned with the restrictive end thereof facing said opposite tube end, the Wall of said head between said portions and said opposite tube end defining an expansion chamber.

2. A lighting device for a main gaseous fuel burner provided with at least one port and having a pilot burner remote therefrom and normall producing a flame, said device comprising a flash tube having one open end positioned adjacent the pilot burner and the opposite open end positioned spaced from the main burner, a tubular head including a pair of telescopic members adapted to be secured in adjusted relation, one of said members being secured to said oppdsite tube end and the other said member terminating in a closed end adjacent the main burner, said other member having a plurality of relatively spaced narrow ribs defining elongated openings in the side wall of said other member adjacent said closed end, said openings being symmetrically arranged around said other member and at least one of said openings being positioned to admit fuel from the one said port of the main burner into said other member, an inlet connection in said closed end for fuel under pressure, a lighter burner projecting from said closed end axially of said head and terminating adjacent said openings to intercept fuel from said one port of the main burner, said lighter burner having an axial port communicating with said connection through which said fuel is adapted to flow and entrain sufficient air through said openings for filling said head and tube with a combustible fuel-air mixture to be ignited from the pilot burner and produce a flame at said lighter burner for igniting the main burner, said head having an interiorly cone-shaped portion projecting from the inner wall thereof between said opposite tube end and said openings in axial alignment with said lighter burner port and being positioned with the restrictive end thereof facing said opposite tube end, the wall of said head between said portion and said opposite tube end defining an expansion chamber. 3. A lighting device for a main gaseous fuel burner provided with at least one port and having a pilot burner remote therefrom and normally producing a flame, said device comprising a flash tube having one open end positioned adjacent the pilot burner and the opposite open end spaced from the main burner, a tubular head including a pair of telescopic members adapted to be secured in adjusted relation, one of said members being secured to said opposite tube end and the other said member terminating in a closed end adjacent said main burner, said other member having a plurality of relatively spaced narrow ribs defining elongated openings in the side wall of said other member adjacent said closed end, said openings being symmetrically arranged around said other member and at least one of said openings being positioned to admit fuel from the one said port of the main burner into said other member, an inlet connection in said closed end for fuel under pressure, a lighter burner carried by said closed end and projecting axially into said head and terminating adjacent said openings to intercept fuel from said one port of the main burner, said lighter burner having an axial port communicating with said connection through which said fuel is adapted to flow and entrain suflicient air through said openings for filling said head and tube with a combustible fuel-air mixture to be ignited from the pilot burner and produce a flame at said lighter burner for igniting the main burner, said one member having an interiorly cone-shaped portion projecting from the inner wall thereof at the other end from said opposite tube end and in axial alignment with said lighter burner port and being positioned with the restrictive end thereof facing said opposite tube end, the wall of said head between said portion and said opposite tube end defining an expansion chamber, said expansion chamber being provided with an aperture in the side wall thereof adjacent the restrictive end of said coneshaped portion, and a collar slidably mounted on said other member and adjustable over said openings to maintain said symmetrical arrangement and control the effective area thereof.

CHARLES K. STROBEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,711,794 Kibele May 7, 1929 2,087,433 Hollman July 20, 1937 2,091,530 Slavin et al Aug. 31, 1937 FOREIGN PATENTS Number Country Date 827,388 France Apr. 25, 1938 

